This is a very easy procedure and came out very much similar to that of the sweet stall taste.
To make I mixed the besan, rice flour salt and then to this I added green chillies and fried onions and sprinkle water as you did to get the same consistency as yours and deep fried in oil and a medium to high but now very high temp. as it may butn the onions. It seriously stayed fresh for more than a week and came out pretty good.
I tried to make the onion pakoda following your receipe and it came out well with respect to taste but is getting soft within two days. I was looking for the sweet stall style and tried a procedure and it clicked.